Movable barrier apparatus and methods for responding to barrier travel obstructions and abnormalities

ABSTRACT

Movable barrier monitoring apparatus and methods are provided for rapidly responding to barrier travel obstructions and other abnormal occurrences to cause the movable barrier operator to halt barrier travel or stop and reverse barrier travel, while ignoring typical and normal impediments to barrier travel. Alternate methods are described for programming the barrier operator controller to compare characteristics of the monitored barrier run over the defined travel path with the characteristics of a good barrier run without interruption to barrier travel, with the degree of differentiation of such characteristics determinative of whether the operator controller is to interrupt barrier travel or not.

CROSS REFERENCE TO RELATED APPLICATIONS

This non-provisional patent application claims the benefit of andpriority to pending U.S. Provisional Patent Application No. 62/662,136,filed Apr. 24, 2018, and entitled “CORRELATION BETWEEN FORCE PROFILEPATTERNS IN MOVABLE BARRIER OPENER SYSTEMS” and pending U.S. ProvisionalPatent Application No. 62/818,354, filed Mar. 14, 2019, and entitled“SLACK CABLE DETECTION IN MOVABLE BARRIER OPENER SYSTEMS” both of whichare hereby incorporated by reference in their entirety for all purposes.

TECHNICAL FIELD

The present invention relates generally to movable barrier openersystems for opening and closing garage doors, gates, and like movablebarriers, and relates in particular to new and improved monitoringapparatus and methods for rapidly responding to only barrier travelobstructions or other abnormal occurrences.

BACKGROUND

Upward acting sectional or single panel garage doors, roll-up doors,gates, and other types of powered movable barriers utilize movablebarrier opener systems for effecting the requisite control over theopening, closing and other movement of the barriers. A typical movablebarrier opener system comprises a movable barrier operator and motor andmotor drive assembly imparting movement to the barrier. The operation ofthe barrier opener system is typically controlled from (i) interior orexterior building mounted consoles, in wired or wireless communicationwith the movable barrier operator, (ii) proximately located hand held orvehicle mounted wireless transmitters, and (iii) remotely locatednetwork (e.g., Internet) access devices. Using such devices, barriermovement commands, typically code encrypted, are transmitted to themovable barrier operator, and in particular to the movable barrieroperator's controller, the latter typically a microprocessor,microcontroller, or other type of programmable platform apparatus. Thecontroller, inter alia, decrypts the received encrypted commands, andbased thereon, instructs the motor, or other motion-imparting powersource, to open, close, halt the travel of, or otherwise move, themovable barrier in accordance with the received commands. When themovable barrier is a garage door (the movable barrier opener systemtherefore referred to as a “garage door opener system” and the movablebarrier operator therefore referred to as a “garage door operator”), thegarage door operator controller must, in addition to its other tasks (i)assure that the force applied by the motor is sufficient to enable thegarage door to uninterruptedly travel along its defined path (typicallya tortious route), while at the same time (ii) assure that anomalous(i.e., abnormal) door travel conditions (such as animate or inanimatedoor obstructions, door imbalance or blockage, or like occurrences) willcause rapid interruption of the door travel (due to the stoppage, orstoppage and reversal, of the motor), while avoiding interruption ofdoor travel due to the normal or typical encounters (e.g., guide railirregularities, friction, scaling factors, or noise).

Thus, there currently exists in the industry the need for a moreeffective and reliable monitoring method that (i) is sufficientlysensitive and responsive to true movable barrier travel obstructions orother abnormal occurrences so as to rapidly interrupt the door travelbefore damage occurs, (ii) is not so overly sensitive to events that donot compel such interruption, and (iii) may be incorporated into themovable barrier operator controller.

While such an effective and reliable method is desired irrespective ofthe type of motor drive assembly that the movable barrier opener systememploys, one type of motor drive assembly, referred to as a jack shaftdrive assembly, is particularly in need of such method. Asconventionally known, a jack shaft drive assembly is one in which,typically, the motor is directly coupled to a horizontally positionedshaft (i.e., the jack shaft) extending along the width of, and mountedabove, the movable barrier, one or more cable drum(s) rigidly attachedto the jack shaft. One or more cables are wound about the cable drum(s)with the free end of each cable connected to, and at the lower end of,the movable barrier. When the motor is actuated to open the door, thejack shaft and the cable drum(s) are consequently rotated in a directionso as to wind the cable(s) onto the cable drum(s), thereby lifting themovable barrier to its open position. When the motor is actuated toclose the door, the jack shaft and the cable drum(s) are consequentlyrotated in an opposite direction so that the cable(s) may be payed out,thereby permitting the movable barrier to be closed by the combinationof the restoring force provided by a torsion spring wound around thejack shaft and the unsupported portion of the weight of the movablebarrier.

Not only does a jack shaft type drive assembly require reliable andaccurate detection of, and immediate stoppage or reversal of the motorin response to, obstructions to door travel, but also immediate motorshut off in the presence of other abnormal occurrences not untypical ofjack shaft drive assemblies. For example, whenever tension is removedfrom a cable, thereby causing the cable to unwrap or separate from acable drum, the cable may then not relocate properly when tension isrestored, and the movable barrier, for this or other reasons, may becomeundesirably stuck or jammed in a partially open or intermediateposition, requiring manual repair work by a technician to correct thesituation. The most common cause of this cable tension removal is whenthe motor rotates the cable drum but the movable barrier does not move.This may occur, for example, when the movable barrier is stuck in itsopened position or an obstruction impedes its movement. Such conditionsare particularly existent when the movable barrier (e.g., garage door)is one of the light weight variety. The automatic closing of any garagedoor inherently introduces vibrations, guide rail irregularities, noise,and other real-world energy dynamics into the process of movement of thedoor. In the case of a light weight door, these dynamics may causevariations in the inertial forces associated with the moving door thatmimics that which occurs when the door becomes jammed or otherwiseobstructed. This can make the discriminatory detection of only trueobstructions or other serious abnormalities more difficult.

In summary, it is desired, particularly for relatively light weightmovable barriers, to have movable barrier opener systems that employmonitoring apparatus and methods that (i) continuously providesufficient, albeit varying, levels of force to uninterruptedly move themovable barrier along its designated route, while at the same time (ii)rapidly respond to only anomalous barrier travel conditions to effectmotor stoppage in the event of true travel obstructions or otherabnormal occurrences, and not in response to normal variations ofbarrier travel. Moreover, it is desired that such objectives be achievedindependent of changes in environmental conditions, such as variationsin ambient temperatures. The new and improved monitoring apparatus andmethods of the present invention described herein accomplish theseobjectives.

SUMMARY

Accordingly, a first embodiment of the invention involves a new andimproved method of movable barrier monitoring that is particularlyuseful when monitoring light weight garage doors and like movablebarriers. This method, as incorporated or programmed into the controllerof the movable barrier operator, broadly determines the difference(herein defined as “door position discrepancy”) between (i) a current“movable barrier behavioral profile” generated during a presentlymonitored travel or “run” of the movable barrier between defined travelpositions, and (ii) a good stored “movable barrier behavioral profile”,representing a successful “run” of the movable barrier betweenessentially identical defined travel positions, without barrier travelinterruption. This good profile can be provided as an initial factorysetting or as generated by one (or more) prior successful run(s) of themovable barrier, without barrier travel interruption, and between theessentially identical defined travel positions.

The term “movable barrier behavioral profile”, as used herein in thespecification and claims, is defined as a set of data representative ofone or more ‘position factors’ over at least a portion of travel of themovable barrier along its defined travel path. A “position factor”, asused herein in the specification and claims, is defined as any factor(i) that is indicative, directly or indirectly, of the position of themovable barrier along its defined travel path, or (ii) by which theposition of the movable barrier along its defined travel path can bedetermined. Thus, a “position factor” can be, for example, extent ofmotor torque, motor current, or motor shaft angular position, specificcombinations of these, or the other examples described in thisapplication. Therefore, a movable barrier behavioral profile may be aset of such representative data undergoing collection during a presentlymonitored “run” or a stored set of such data from one or more priorsuccessful run(s).

In accordance with the method and apparatus of this first embodiment,the deviation of one or more position factors making up a movablebarrier behavioral profile from an expected value is compared to apre-set acceptable deviation criteria. The pre-set acceptable deviationcriteria, for example, may be programmed into the controller, initiallyor as a consequence of an earlier good run, set by a user at the time ofinstallation of the movable barrier opener, and/or set proportional tothe movable barrier weight, mass, or other characteristic. So long asthe deviation is within the pre-set acceptable deviation criteria, themovable barrier will travel along its defined path, withoutinterruption. However, in the event of deviation of one or more of theposition factors of the particular movable barrier behavior profilebeyond the pre-set acceptable deviation criteria (therefore indicativeof a true obstruction or other abnormality), immediate stoppage, orstoppage and reversal, of the motor (or other motion-imparting powersource), and therefore of the movable barrier, occurs.

Thus, fluctuations or deviations, even severe fluctuations ordeviations, of the monitored position factor do not compel motor (orbarrier travel) interruption during the barrier's run, so long as suchfluctuations or deviations are within the pre-set acceptable deviationcriteria Rather, immediate stoppage, or stoppage and reversal, of themotor (and thus, barrier travel) is ultimately depends upon the doorposition discrepancy, i.e., the difference between the currentlymonitored movable barrier behavioral profile and a “good” door movablebarrier behavioral profile exceeding the pre-set acceptable deviationcriteria.

In accordance with a feature of the aforedescribed monitoring, the doorposition discrepancy can be determined when the respectively definedmovable barrier travel paths are between the barrier's fully open andfully closed positions or, alternatively, during only select portionsthereof (e.g., the last portion of the travel path, an intermediateportion of the travel path, or an initial portion of the travel path).

A second embodiment of the invention involves a new and improved forcemonitoring method incorporated or programmed into the controller of themovable barrier operator that automatically determines the degree ofcorrelation, referred to herein as the “correlation coefficient”,between (i) a “force factor” profile pattern generated by the currentlymonitored travel or “run” of the barrier between defined travelpositions, and (ii) a “good” stored “force factor” profile pattern,provided either as a factory setting or generated by a prior successfulrun of the barrier, without barrier travel interruption, betweenessentially identical defined travel positions. By way of example, whenthe two profile patterns are identical, the correlation coefficientwould be 1.0, with lesser degrees of correlation having correspondinglysmaller coefficients in accordance with the computational methods ofthis process.

The “force factor”, as defined herein, is any factor that relates,directly or indirectly, to the measure of force being supplied by themotor to move the movable barrier along its defined travel path. Thus, aforce factor may be the measure of motor torque, motor current or motorspeed, rate of change of motor current, back EMF, motor voltage, or likemeasures, as well as specific combinations of various ones of suchfactors. Thus, the term “force factor profile pattern”, as used herein,shall mean either the profile pattern of the specific force factorrepresentative of the measure of such motor force, or the force profilepattern itself resulting from use of the specific force factor.

The correlation coefficient, taken in conjunction with pre-setacceptable comparison criteria programmed into the controller, assuresuninterrupted movable barrier travel for the currently monitored run solong as it is within the aforementioned pre-set acceptable comparisoncriteria, but also enables immediate stoppage, or stoppage and reversal,of the motor (or other motion-imparting power source), and therefore ofthe barrier travel, if the correlation coefficient does not meet (i.e.,is below) the pre-set acceptable comparison criteria.

In accordance with a feature of this method of the invention, thecorrelation coefficient can be determined when both the “good” andcurrently monitored runs of the barrier are from fully open to fullyclosed or, alternatively, during only select portions thereof (e.g., thelast portion of the travel path, an intermediate portion of the travelpath, or an initial portion of the travel path).

Of note is that the monitored force factor does not compel motor (orbarrier travel) interruption due to only fluctuations, even severefluctuations, of the force factor during the run of the barrier but,rather, is instead based upon the lack of degree of correlation betweenthe stored force factor profile pattern and the currently monitoredforce factor profile pattern.

Another feature of this monitoring method of the present invention,particularly as incorporated in the movable barrier operator controller,is the programmed selection of a pre-set acceptable comparison criteriabetween the compared force factor profile patterns, and hence, whetherthe barrier travel is, or is not, to be interrupted. In addition,alternate means are provided for computation of a system's correlationcoefficient.

BRIEF DESCRIPTION OF THE DRAWINGS

Additional features of the new and improved methods and apparatus of thepresent invention will become readily understood from the followingdetailed written description, taken in conjunction with the appendeddrawings, in which:

FIG. 1 is a functional block diagram of material portions of a movablebarrier opener system employing a typical jack shaft motor driveassembly;

FIG. 2A is a pictorial view of material structural components of a jackshaft motor drive assembly for moving a single panel type garage door;

FIG. 2B is a perspective view of material structural components of ajack shaft motor drive assembly for moving an upward acting sectionaltype garage door;

FIG. 3 is a graph in accordance with the first embodiment of theinvention, comparing a first movable barrier behavioral profile from atleast one prior successful movable barrier run, without door travelinterruption, with the monitored movable barrier behavioral profile of acurrent movable barrier run over the same route, the respective movablebarrier behavioral profiles derived, for example, from measured motorcurrent and measured motor jack shaft position during the respectivedoor runs, force being proportional to motor current;

FIG. 4 is a graph in accordance with the first embodiment of theinvention, comparing a second movable barrier behavioral profile from atleast one prior successful movable barrier run, without door travelinterruption, with the monitored movable barrier behavioral profile of acurrent movable barrier run over the same route, the respective movablebarrier behavioral profiles derived, for example, from measured motorcurrent and measured motor jack shaft position during the respectivedoor runs, force being proportional to motor current;

FIG. 5 is a graph in accordance with the first embodiment of theinvention, showing movable barrier behavioral profiles, without doortravel interruption, over the entire route of the movable barrier runfrom one end to the other end, and displaying the measured motor currentand measured motor shaft position during the respective door runs, forcebeing proportional to motor current;

FIG. 6 depicts a flow diagram of the method of monitoring movablebarrier closure, including the measurement of motor current as aposition factor, in accordance with the first embodiment of theinvention;

FIG. 7 depicts a flow diagram of the method of monitoring movablebarrier closure, including the measurement of accumulated door positiondiscrepancy, in accordance with the first embodiment of the invention;

FIG. 8A is a graph in accordance with the second embodiment of theinvention, comparing a stored monitored force factor profile patternfrom a prior successful garage door run, without door travelinterruption, with the monitored force factor profile pattern of acurrent garage door run over the same route, the respective force factorprofile patterns derived, for example, from raw measured motor currentduring the respective door runs, force being proportional to motorcurrent;

FIG. 8B shows the correlation coefficient (degree of correlation)between the two force factor profile patterns of FIG. 8A;

FIG. 9A shows a scaled and offset version of the comparison of the forcefactor profile patterns of FIG. 8A for the same garage door runs;

FIG. 9B shows the correlation coefficient (degree of correlation)between the two force factor profile patterns of FIG. 9A;

FIG. 10A is a graph in accordance with the second embodiment of theinvention, comparing the stored force profile factor pattern (Profile102) of a prior successful garage door run, without door interruption,with the monitored force factor profile pattern (Profile 104) of anunsuccessful (anomalous) garage door run, the respective force factorprofile patterns derived, for example, from raw measured motor currentduring the respective door runs;

FIG. 10B shows the calculation of the correlation coefficient (degree ofcorrelation) between the two force factor profile patterns of FIG. 10A

FIG. 11A is a graph comparing the force factor profile pattern (Profile102) of a prior successful garage door run like that shown in FIG. 10A,with the currently monitored force factor profile pattern (Profile 104)of the unsuccessful garage door run of FIG. 10A, with noise added;

FIG. 11B shows the calculation of the correlation coefficient (degree ofcorrelation) between the force factor profile patterns of FIG. 11;

FIG. 12A is a graph in accordance with the second embodiment of theinvention, comparing the force factor profile pattern (Profile 1204) ofan unsuccessful (anomalous) garage door run, in which the door is stuckin the fully open position, with the stored force factor profile pattern(Profile 1202) of a previously successful garage door run, and alsocompared with the force factor profile pattern (Prediction 1206) of amodeled or predicted force profile;

FIG. 12B shows the correlation coefficient (degree of correlation)between the force factor profile pattern of the unsuccessful run andeither of the force factor profile patterns of the successful run or thepredicted force profile of FIG. 12A;

FIG. 13A is a graph in accordance with the second embodiment of theinvention, comparing a scaled and offset version of the force factorprofile pattern (Profile 1204) of the unsuccessful currently monitoredgarage door run of FIG. 12A with the stored force profile pattern(Profile 1202) of a previously successful garage door run;

FIG. 13B shows the correlation coefficient (degree of correlation)between the force factor profile patterns of FIG. 13A; and

FIG. 14 depicts a flow diagram of the method of monitoring movablebarrier closure, including determination of force correlationcoefficient compared to acceptable comparison criteria, in accordancewith the second embodiment of the invention.

DETAILED DESCRIPTION

Because the monitoring methods of the present invention have been foundto have particular applicability when incorporated into a movablebarrier system of the type employing a jack shaft type motor driveassembly, the following detailed description will be of a preferredembodiment of a garage door opener system incorporating such driveassembly for controlling the movement of the associated garage door.However, it is to be emphasized that the alternative monitoring methodsof the present invention, as subsequently described, may be utilized andincorporated into movable barrier opener systems of any type, employingany type of drive assembly, for controlling the movement of any type ofpowered barrier.

Therefore, with initial reference to FIG. 1, a jack shaft type garagedoor opener system 10 comprises, within power head 12, a garage dooroperator controller 14, DC motor 18, and receiver 20, DC power supply 16providing power to those components through conductive pathways 43. Thepower supply 16 is typically fed from an external AC source 11, normallyelectrical mains.

Door movement commands (e.g., “open,” “close,” “halt”) can beproximately transmitted from interior and exterior wired or wirelesswall consoles (not depicted), as well as from hand-held or vehiclemounted wireless transmitters to receiver 20 where they routed to thedoor operator controller 14 via path 40. The controller 14 comprises anyprogrammable platform apparatus, such as a programmable microprocessoror microcontroller for, in addition to carrying out the monitoringprocessing of the present invention, processing the incoming doormovement commands to instruct operation of the motor 18 (via conductivepath 41) to control movement of the motor 18 (and coupled motor driveassembly) in accordance with the incoming door movement commands.

As illustrated in FIGS. 1, 2A and 2B, the motor drive assembly in thispreferred embodiment comprises a horizontally extending shaft 22 (i.e.,the jack shaft) directly coupled to, and adapted to be rotatably drivenby, motor 18 in either a clockwise or counterclockwise direction. Atorsion spring 25 extends around jack shaft 22 (FIG. 2B). One or morecable drums 24 are rigidly connected to the jack shaft 22, with cables27 wound about the cable drum(s) 24 with the free end of each cableconnected to, at the lower portion of, the garage door 28.

FIG. 2A illustrates the garage door 28 as a conventional single paneldoor being moved between open and closed positions along guide rails 26,and FIG. 2B illustrates the garage door 28 as a conventional upwardacting sectional door being moved between open and closed positionsalong guide rails 26. When motor 18 is instructed by controller 14 toopen the door, the jack shaft 22 and connected cable drums 24 arerotated by the motor 18 in a direction so as to wind the cable(s) 27onto the cable drum(s) 24, thereby lifting the garage door 28 to itsopen position. When the motor 18 is instructed by the controller 14 toclose the door, the jack shaft 22 and connected cable drums 24 arerotated by the motor 18 in the opposite direction so that cable(s) 27may be payed out, thereby permitting the door 28 to be closed, thetorsion spring 25 providing a counterbalance to aid in the door 28 beingmoved to its closed position.

A. First Embodiment of Invention (Position Factor Comparison Approach)

In accordance with the first embodiment of the invention, the movablebarrier operator controller 14 is configured and programmed to (i)monitor the particular chosen position factor that is indicative of theposition of the movable barrier, here the garage door 28, and (ii) fromsuch monitoring, determine whether the door position discrepancy, aspreviously defined, is, or is not, within the pre-set acceptabledeviation criteria, during the travel of the garage door 28 along itsdefined travel path. For example, if motor current is chosen as theposition factor, motor current being proportional to the extent ofrotation of jack shaft 22, and therefore of the position of garage door28, a suitable motor current sensor is positioned in operativerelationship with motor 18 and controller 14. The controller 14,monitoring the motor current, then, pursuant to its programming,determines the door position discrepancy, namely the difference betweenthe amount of motor current during the currently monitored run, orportion of the run, of the door 28 and that during, for example, a prior“good” run of the same run, or portion of the run. If such differenceexceeds the pre-set acceptable deviation criteria, the controller halts(or halts and reverses) the motor, and therefore the travel of the door.If within such criteria, the controller 14 continues to operate themotor and move the door 28 along on its travel path. Therefore, by usingthis method of monitoring the particular position factor, and accuratelysetting the pre-set acceptable deviation criteria, the interruption ofdoor travel is limited to only those situations in which the doorposition discrepancy is indicative of only a true obstruction orspecific abnormal occurrence.

While this previously described monitoring method has been determined tobe effective for typical movable barrier opener systems under mostoperational situations, challenges may still occur when the movablebarrier or garage door is of the light weight variety and when the dooris to be moved from its fully open position toward its fully closedposition. This is because the “vertical weight” of a light weight door(i.e., the downward gravitational pull on the vertically hanging portionof the door as opposed to the portion lying horizontally at rest) andthe corresponding counterbalancing spring force are so small. As aconsequence, under such circumstances, detecting when such light weightdoor is jammed becomes more difficult than detecting when a heavier dooris jammed.

Explaining differently, if one was to model a door with a linear springand a linear force actuator, neglecting friction and the rotatingportion, one has

${{{m\overset{¨}{x}} + {\left( {\frac{m\; g}{h} - k} \right)x}} = F},$

where F is the motor force,

$\frac{m\; g}{h}x$

is the vertical weight of the door, kx is the spring force, and m{umlautover (x)} is the resulting accelerating force experience by the door. Ona light door, m is small, and

${\left( {\frac{m\; g}{h} - k} \right)x},$

the open limit, is even smaller. On a well-balanced door,

$\left( {\frac{m\; g}{h} - k} \right)$

is not large, and on a light, well-balanced door, it is even smaller,and in the open limit, x is a close to zero. Consequently, the wholestatic force becomes difficult to distinguish from extraneous factorssuch as normal friction and the dynamic forces of starting the motor andturning the jack shaft.

However, to overcome this challenge, and in accordance with a feature ofthis embodiment of the invention, during the movement of the door 28from its open position toward its closed position, the controller 14 isprogrammed to periodically brake the motor by providing a momentaryreversal pulse to the motor 18, the controller 14 then measuring themotor current drawn by motor 18 as a consequence of the momentaryreversal pulse compared to the motor current drawn without suchmomentary reversal pulse. If the movable barrier 28 is jammed, themechanical load presented by the door 28 is necessarily diminished. Thisdiminishes the inertia of the combined moving mass of the system (motor18, jack shaft 22, and door 28), the door 28 no longer mechanicallyloading the jack shaft 22. As such, the motor current drawn by the motor18 and measured by the controller 14 as a consequence of the momentaryreversal pulse is less than the motor current drawn by the motor 18 andmeasured by the controller 14 when the door 28 was still mechanicallyloading the jack shaft 22, the difference being outside of the pre-setacceptable deviation criteria. This then results in the controllerstopping the motor 18, or more desirably stopping and reversing themotor 18, thereby responsively tightening the cables 27 and raising thejammed door 28 back toward its open position. Thus, by implementingthese periodic momentary reversal pulses during the monitoring of theposition factor, here motor current, in accordance with the method ofthis embodiment of the invention, the difference between a light weightmoving door and one that is stuck or jammed can be detected.

The aforementioned description has been in the context of the positionfactor being motor current. However, other measures monitored by thecontroller 14 can be similarly be used to achieve the desiredobjectives. For example, the controller 14 may measure an elapsed timefrom the instant the controller 14 provided the momentary reversal pulseto the motor 18, to the instant that the motor current drawn by themotor 18 peaks in connection with such momentary reversal pulse comparedto the time that the motor current peaks on a previous good run.Alternatively, the controller 14 may provide momentary reversal pulsesat known intervals and the controller 14 may measure an elapsed timefrom the instant that the motor current drawn by the motor 18 peaks to astored instant that the motor current peaked on previous good runs ofthe movable barrier 28.

A motor 18 under a relatively greater load (higher torque) will exhibita particular delay (e.g., a “first delay” or a “loaded delay”) betweenthe instant that the momentary reversal pulse was provided to the motor18 and the instant that the motor current peaks, whereas a motor 18under a relatively lesser load (lower torque) will exhibit a differentdelay (e.g., a “second delay” or an “unloaded delay”) between theinstant that the momentary reversal pulse was provided to the motor 18and the instant that the motor current peaks. Similarly, a known goodrun of a movable barrier 28 driven by the motor 18 without obstructionwill include a motor current peak at a relatively later moment in timefollowing the start of motor 18 movement or provision of a momentaryreversal pulse (e.g., a “first delay” or a “loaded delay”) than a motor18 driving an obstructed movable barrier which will include a motorcurrent peak at a relatively earlier moment in time following the startof motor 18 movement or provision of a momentary reversal pulse (e.g., a“second delay” or an “unloaded delay”). Because the first delay and thesecond delay have different lengths, the controller 14 may characterizethe load condition of the motor 18 based on the magnitude of the firstdelay and the second delay and thus may determine whether the movablebarrier is moving correctly or is jammed.

As another example, the chosen position factor may be the angularposition of the output shaft of the motor. Thus, an encoder may beoperatively coupled to the motor 18 and the controller 14 that providesthe angular position of the motor shaft, the rotation of the motor shaftcorresponding to the extent and direction of movement of the door 28.The encoder may provide periodic position pulses corresponding to theextent of angular movement of the shaft of the motor 18. By countingthese pulses, the controller 14 may determine the position of themovable barrier. One type of suitable shaft encoder is an absoluteposition encoder that typically digitally determines the angles of twogears with different tooth counts, providing a fine and a coarseposition reading that is combined to determine the absolute position ofthe shaft. However, a movable barrier may jam while the position of theshaft of the motor continues to change because the cable may come off ofthe drum 24 and the motor 18 may continue to rotate the jack shaft 22while the jammed movable barrier unexpectedly fails to move.

By counting these periodic position pulses from the encoder or receivingthe measured motor shaft position, the controller 14 may also associatean expected motor shaft position with each motor current peak when thecontroller 14 periodically brakes the moving motor 18 by providing amomentary reversal pulse to the motor 18. A motor 18 driving anobstructed movable barrier will include a motor current peak at arelatively earlier moment in time following the start of motor movement(e.g., closer in time to the provision of the momentary reversal pulse)and thus a relatively lesser position pulse count or lesser motor shaftposition than a motor 18 driving an unobstructed movable barrier, whichwill include a motor current peak, at a relatively later moment in timefollowing the start of motor movement (or provision of a momentaryreversal pulse). Because the first delay and the second delay havedifferent lengths, the controller 14 may characterize the load conditionof the motor 18 based on the position of the shaft of the motor 18 asrepresented by the position pulse count or measured motor shaft positionat the time of the motor current peak. When motor current peaks begin tooccur uncharacteristically early, a movable barrier may be determined tohave become jammed.

By characterizing the load condition of the motor 18 based on theposition of the shaft of the motor 18 as represented by the positionpulse count or measured motor shaft position at the time of the motorcurrent peak, the controller 14 may detect the jammed state of the door28 without needing to measure the difference of the time of momentaryreversal pulse to the time of motor current peak. Instead, momentaryreversal pulses may be provided at set known intervals, and the positionpulse count or measured motor shaft position corresponding to the motorcurrent peak that arises after the momentary reversal pulse will bemeasured.

In other words, regular, periodic momentary reversal pulses areprovided, and rather than timing the duration between providing thepulse and recording a current peak, the controller 14 records the motorshaft position at the time of the current peak and compares to the motorshaft position at a time of a current peak recorded from a knownunobstructed “good” run. Thus, the position pulse count or measuredmotor shaft position at the moment of the motor current peak maycorrespond to a scaled and offset value of the delay between providingthe pulse and recording a current peak. As such, the position pulsecount or measured motor shaft position may be a proxy measurement for a“loaded delay” for a motor 18 driving an unobstructed movable barrierand also may be a proxy measurement for the “unloaded delay” for a motor18 driving an obstructed movable barrier.

As a further feature of this approach when the door may be of the lightweight type, multiple momentary reversal pulses may be provided to themotor 18 in sequence and the difference in position pulse count ormeasured motor shaft position of the current monitored run with that ofa known good run, or the delay between each momentary reversal pulse andthe instant that the motor current peaks, can be summed for eachmomentary reversal pulse. This summation develops an accumulatedposition error over time. As multiple momentary reversal pulses areprovided and multiple motor current peaks are observed, the fluctuationsassociated with a practical system and the variation and noise generatedthereby cancel out and trends emerge.

In this manner, the accumulated error between the exhibited delay andthe expected delay may be measured by the controller 14 to characterizethe load condition of the motor. By comparing the accumulated error overa known number of reversal pulses, and comparing this accumulated errorto a threshold, the controller 14 may determine if the motor 18 hasbecome unloaded (e.g., the moving mass of the movable barrier 28 is nolonger coupled to the motor 18 because the cable 27 between the jackshaft 22 and the door 28 has become slack). This indicates that themovable barrier 28 is jammed.

Thus, one may appreciate that the controller 14 may also identify that amovable barrier 28 is jammed by the controller 14 (i) measuring themotor current peak (as the position factor) arising in connection with amomentary reversal pulse and comparing the measured motor current to anexpected value, (ii) measuring the delay (as the position factor)between the momentary reversal pulse and the motor current peak arisingin connection with the momentary reversal pulse and comparing to anexpected value, (iii) measuring the difference of the motor shaftposition (as the position factor) associated with a motor current peakof the current run of the movable barrier with the motor shaft positionassociated with a motor current peak of a known “good run” of themovable barrier, (iv) comparing multiple measured delays between themomentary reversal pulse and the current peak arising in connection witheach momentary reversal pulse and summing the multiple measured delaysto generate an accumulated door position discrepancy over time, and (v)measuring and comparing multiple motor shaft positions connected withmultiple motor current peaks, each from a corresponding one of multiplemotor shaft positions connected with multiple motor current peaks of aknown good run of the movable barrier 28 to generate an accumulated doorposition discrepancy over time. In each case, the position factor iscompared to a programmed pre-set acceptable deviation criteria. If theposition factor exceeds this criteria, the door is determined to bejammed.

In accordance with this described monitoring process, the controller 14may compare the position factor with the pre-programmed pre-setacceptable deviation criteria. If the position factor is within theacceptable deviation criteria, then the controller 14 is configured toinstruct the motor 18 to continue to move the door 28 along its definedtravel path without any interruption of door travel. On the other hand,if the position factor, at any portion of the defined travel path, is(or becomes) not within the pre-set acceptable deviation criteria, thecontroller 14, therefore assessing that the movable barrier 28 hasencountered a true travel obstruction or an abnormal occurrence such asa loss of tension in the cable 27, is configured to immediately respondby stopping, or stopping and reversing, the motor 18, and therefore themovable barrier 28.

In some situations, there may be variable pre-set acceptable deviationcriteria programmed into the controller 14 for respectively differentportions of the defined travel path, to allow for different forces to beapplied to the movable barrier 28, or even for no restrictions on theforce to be applied, such as at the beginning or the end of the travelpath. Moreover, the sequence of momentary reversal pulses mentionedabove may be confined to a subset of the travel path, such as at thebeginning of the travel path.

Utilizing this embodiment of the monitoring method of the presentinvention that essentially compares the movable barrier behavioralprofile of the current run with the movable barrier behavioral profileof a prior successful run, as opposed to an approach that is basedsolely upon the presence or absence of force spikes in the monitoredmovable barrier behavioral profile, not only reduces the number ofneedless door travel interruptions, but enables responses to abnormaloccurrences that may not otherwise be identified.

In accordance with a feature of this described embodiment, the pre-setacceptable deviation criteria can be defined, for example, as a numberin the range of 0% to 100% where a measured value such as the measuredmotor current, delay between a momentary reversal pulse and a currentpeak, and/or an accumulated door position discrepancy is compared to anexpected value. 0% may indicate that the measured value is 0% of theexpected value, and 100% may indicate that the measured value is 100% ofthe expected value. In various instances, the measured value andexpected value are unsigned absolute values. This acceptable deviationcriteria provides a mechanism for characterizing the similarity of thecurrently monitored movable barrier behavioral profile and the “good”stored movable barrier behavioral profile. If the pre-set acceptabledeviation criteria is then programmed into the controller 14 to be lessthan a perfect match of the profiles, for example an 80% match, then thecontroller 14 causes the motor 18 to stop, or to stop and reverse, whenthe compared profiles fall outside the acceptable deviation criteria. Ofcourse, the acceptable deviation criteria can be pre-set, higher orlower than 80%, depending upon the desired sensitivity, and can also beset at variable percentages depending upon the location(s) in thedefined travel path, but 80% is used herein as merely an illustrativeexample.

Having completed an overall description of this first embodiment of thesystem and method of the invention of movable barrier monitoring anddetection of true obstructions and other abnormal occurrences, referenceis directed to FIG. 3 of a graph 300 comparing a first movable barrierbehavioral profile from at least one prior successful garage door run(Profile 303), without door travel interruption, with the monitoredmovable barrier behavioral profile (Profile 301) of a current garagedoor run over the same route, the respective movable barrier behavioralprofiles derived, for example, from measured motor current 320 andmeasured motor shaft position 340 during the respective door runs.

Motor current 304 corresponds to the current drawn by a motor 18attempting to close a jammed garage door 28 (“fault state motor current”304) and motor current 302 corresponds to the current drawn by a motor18 attempting to close a properly functioning garage door 28 (“nominalmotor current” 302). The motor current difference 305 between thenominal motor current 302 and the fault state motor current 304 iscalculated by the controller 14 by measuring the difference between thenominal motor current 302 stored by the controller 14 and the detectedmotor current 304 measured during the current run.

Motor shaft position 340 also reveals whether a door 28 is properlyfunctioning or jammed. For instance, a motor 18 turning to lower amovable barrier 28 will exhibit a spike in motor current 304 upon beingdriven with a momentary reversal pulse. The elapsed time between themomentary reversal pulse and the spike will be different for a motor 18that is under a heavier load (e.g., at least partially supporting amovable barrier 28 than for a motor 18 that is under a lighter load(e.g., the movable barrier 28 is jammed and the motor 18 is unwinding acable that would suspend the movable barrier 28 if it were not jammed).However, rather than measuring time, an encoder on a motor shaft maymeasure motor shaft position 340 as a proxy for time. Thus, a successfulmovable barrier run (Profile 303) shows a peak at a nominal motor shaftposition 306 and a monitored movable barrier behavioral profile (Profile301) of a run where the door 28 is jammed shows a peak at a fault motorshaft position 308. The fault-to-nominal motor shaft position difference307 between the nominal motor shaft position 306 and the fault motorshaft position 308 is calculated by the controller 14 by measuring thedifference between the nominal motor shaft position 306 stored by thecontroller 14 and the detected motor position (fault motor shaftposition 308) measured during the current run. The difference betweenthese two positions may be termed a “position factor.” This “positionfactor” may be compared to an expected value (a “pre-set acceptablecomparison criteria”).

With reference to FIG. 4, an important property is illustrated incomparison to FIG. 3. FIG. 4 shows aspects of a system and method formovable barrier monitoring of the movement of a relatively light weightmovable barrier. A graph 400 demonstrates the usefulness of calculatingan accumulated door position discrepancy for identifying error statesthat otherwise might be overlooked. Graph 400 also shows a first movablebarrier behavioral profile from at least one prior successful movablebarrier run (Profile 303), without door travel interruption, with themonitored movable barrier behavioral profile (Profile 301) of a currentmovable barrier run over the same route, the respective movable barrierbehavioral profiles derived, for example, from measured motor current320 and measured motor shaft position 340 during the respective doorruns.

Motor current 304 corresponds to the current drawn by a motor 18attempting to close a jammed movable barrier 28 (“fault state motorcurrent” 304) and motor current 302 corresponds to the current drawn bya motor 18 attempting to close a properly functioning movable barrier 28(“nominal motor current” 302). The motor current difference 305 betweenthe nominal motor current 302 and the fault state motor current 304 iscalculated by the controller 14 by measuring the difference between thenominal motor current 302 stored by the controller 14 and the detectedmotor current 304 measured during the current run. Notably however, themotor current difference 305 is relatively small and potentially withina range of variation and noise within a practical system. Thus, meremonitoring of motor current 304 may fail to reveal the fault condition.

Motor shaft position 340 also reveals whether the door 28 is properlymoving or is jammed. For instance, a motor 18 turning to lower a movablebarrier 28 will exhibit a spike in motor current 304 upon being drivenwith a momentary reversal pulse. The elapsed time between the momentaryreversal pulse and the spike will be different for a motor 18 that isunder a heavier load (e.g., at least partially supporting a movablebarrier 28 than for a motor 18 that is under a lighter load (e.g., themovable barrier 28 is jammed and the motor 18 is unwinding a cable thatwould suspend the movable barrier 28 if it were not jammed). However,rather than measuring time, an encoder on a motor shaft may measuremotor shaft position 340 as a proxy for time. Thus, a successful movablebarrier run (Profile 303) shows a peak at a nominal motor shaft position306 and a monitored movable barrier behavioral profile (Profile 301) ofa run where the door 28 is jammed shows a peak at a fault motor shaftposition 308. The fault-to-nominal motor shaft position difference 307between the nominal motor shaft position 306 and the fault motor shaftposition 308 is calculated by the controller 14 by measuring thedifference between the nominal motor shaft position 306 stored by thecontroller 14 and the detected motor position (fault motor shaftposition 308) measured during the current run. The difference betweenthese two positions may be termed a position factor. This difference maybe compared to an expected value (a “pre-set acceptable deviationcriteria”). However, this position factor may fall within the pre-setacceptable deviation criteria because the inertial contribution of aparticularly light (or horizontally traveling) door does not induce anappreciable fault-to-nominal motor shaft position difference 307.

To resolve these concerns, a controller 14 may calculate thefault-to-nominal motor shaft position difference 307 and store thisvalue. Multiple momentary reversal pulses may be provided so thatmultiple spikes in motor current 304 are generated. As such, multiplefault-to-nominal motor shaft position differences 307 will be produced.Each may be measured and then added to the stored value. In this manner,an accumulated door position discrepancy may be calculated over time.The accumulated door position discrepancy will reflect the jammed natureof a jammed door 28 as the motor shaft position increasingly lagsexpectations because the door 28 is not providing an expected inertialcontribution to the moving mass of the system (motor 18, jack shaft 22,movable barrier 28). Because the motor shaft position increasingly lagsexpectations, this lagging trend will emerge from the noise andvariations in data collected in a practical installation.

In various circumstances, the series of momentary reversal pulses may beprovided over only a portion of the run of the garage door 28. Thecontroller 14 may be configured to begin the comparison of the movablebarrier behavioral profiles during an initial portion of a movement ofthe door 28, rather than for an entire duration of its travel. Moreover,the initial stored “good” movable barrier behavioral profile may begenerated during either a “learn” mode or “operate” mode of thecontroller 14.

For example, FIG. 5 shows a graph 500 of motor current 320 and motorshaft position 340 for an entire end-to-end run of a movable barrier.Notably, graphs 300 and 400 (FIGS. 3 and 4) which show a series ofmomentary reversal pulses, are confined to the initial portion of therun of the movable barrier 28. In various instances, this portion of therun corresponds to a portion of travel wherein part or all of themovable barrier 28 is horizontal so that the contribution of gravity toovercoming potential jams is diminished. However, in other instances,the momentary braking pulses may be provided for the entirety of the runof the movable barrier 28.

With reference now to FIG. 6, a flowchart depicts an example method 600of operating a movable barrier opener system in accordance with thisembodiment of the invention. Accordingly, the method may includedriving, by the controller 14, the motor 18 to close the garage door 28(block 610). The controller 14 may momentarily reverse the motor 18(block 620). The controller 14 may then measure the position factor, forexample, peak motor current associated with the reversal (block 630).The position factor (here, peak motor current) is compared to athreshold (block 640). If the position factor (here, peak motor current)fails to satisfy the threshold (e.g., is less than expected), then thecontroller 14 may stop and reverse the motor 18 because this conditionis associated with the door 28 having jammed or become obstructed duringtravel in a closing (e.g., downward) direction. (block 650). If thecurrent satisfies the threshold, then the motor 18 continues to bedriven (block 610).

With reference to FIG. 7, a flowchart is provided depicting a furtherexample 700 of operating a movable barrier opener system in accordancewith this embodiment of the invention. The method may include driving,by controller 14, the motor 18 to close the garage door 28 (block 610).The controller 14 momentarily reverses the motor 18 (block 620). Thecontroller 14 then measures a position factor, for example motor shaftposition at the point of peak motor current associated with themomentary motor reversal and may calculate a door position discrepancycorresponding to the difference of this position factor and the sameposition factor for a known good run (block 710). This door positiondiscrepancy may be added to an accumulated door position discrepancy(block 720). The accumulated door position discrepancy may be comparedto a pre-set acceptable deviation criteria (block 730). In response tothe accumulated door position discrepancy not being within the pre-setacceptable deviation criteria, then the controller 14 may stop andreverse the motor 18 because this condition is associated with themovable barrier 28 having jammed or become obstructed during travel in aclosing (e.g., downward) direction (block 650). If the accumulated doorposition is within the pre-set acceptable deviation criteria, then thecontroller 14 continues to drive the motor 18 to close the door 28(block 610).

As an alternative to comparing a currently monitored movable barrierbehavioral profile with a stored movable barrier behavioral profile froma prior successful run, a currently monitored movable barrier behavioralprofile may preferably be compared with a model of a movable barrierbehavioral profile. The model is initially generated by performing alinear least squares fit to a known “good” monitored movable barrierbehavioral profile (i.e., during a barrier run where obstructions orabnormal occurrences were not encountered). If each currently monitoredmovable barrier behavioral profile satisfies the acceptable deviationcriteria, then the currently monitored movable barrier behavioralprofile is incorporated into the model. One mechanism of incorporatingevolving data into the model is by expanding a linear least squares fitthat generates the model to include the data from the currentlymonitored movable barrier behavioral profile. Therefore, the model iscontinually updated over time.

B. Second Embodiment of Invention (Correlation Approach)

In accordance with the second embodiment of the invention, thecontroller 14 is configured and programmed to (i) monitor a chosen forcefactor that is indicative of the force applied by the motor 18, (ii)then replicate therefrom the “force factor profile pattern”, aspreviously defined, during the door's travel along a defined travelpath, (iii) then compare the force factor profile pattern of thecurrently monitored door run with the force factor profile pattern of a“good” run along the identical defined travel path, without any barriertravel interruptions, to determine the difference between them, or the“force profile discrepancy”, (iv) determine the “correlationcoefficient” based upon this force profile discrepancy, and (v)determine whether the correlation coefficient is, or is not, within thepre-set acceptable comparison criteria, the latter indicative of anobstruction or abnormality, resulting in the controller 14 stopping (orstopping and reversing) the motor 28, the former resulting in thecontroller 14 continuing to drive motor to close the door.

Any suitable force factor indicative of force applied by a motor may bechosen to be monitored by the controller 14. For example, in thefollowing description, motor current drawn by the motor 18 is chosen dueto force applied by a motor being directly proportional thereto. One mayalso have chosen, for example, motor speed, force applied by a motorbeing inversely proportional to motor speed.

The monitoring method of this invention can apply to the entirety, orany portion, of the defined travel path of the garage door 28 betweenits open and closed limits. However, as an example, and because accurateand reliable detection of obstructions and abnormal occurrences areparticularly challenging under the circumstances of a motor driven jackshaft type drive assembly moving a garage door from its open to closedposition. Accordingly, with reference to the flow diagram of FIG. 14,the monitoring method 1400 is depicted with motor 18 initially beingdriven by controller 14 to close garage door 28 [block 610]. Controller14, monitoring the current drawn by motor 18, replicates the forcefactor profile pattern of the currently monitored “run” of the door 28[block 1410]. The controller 14 next mathematically compares itsso-replicated force factor profile pattern with a stored force factorprofile pattern, the latter resulting either from an initial factorysetting, or from a prior “good” run, but without any door travelinterruptions along the entire defined travel path. This comparisonproduces a calculated force profile discrepancy [block 1429], from whichthe controller determines the correlation coefficient [block 1430].

The controller 14 then compares this computed correlation coefficientwith pre-set acceptable comparison criteria (i.e., sufficiently highpre-set correlation coefficient) to determine whether the correlationcoefficient is within the pre-set acceptable comparison criteria (i.e.,whether the correlation coefficient is at least as high as the pre-setcorrelation coefficient) (block 1440). If the computed correlationcoefficient is within the acceptable comparison criteria (i.e., at thedesired correlation coefficient level), then the controller 14 isprogrammed to instruct the motor to continue to move the door along itsdefined travel path without any interruption of door travel (block 610).On the other hand, if the correlation coefficient, at any portion of thedefined travel path, is (or becomes) not within the pre-set acceptablecomparison criteria (i.e., below the desired correlation coefficientlevel, the controller 14, therefore assessing that the garage door 28has encountered a true travel obstruction or an abnormal occurrence suchas a loss of tension in the cable 27, immediately responds by stopping,or stopping and reversing, the motor, and therefore the garage door 28(block 650).

In some situations, there may be variable pre-set acceptable comparisoncriteria programmed into the controller 14 for respectively differentportions of the defined travel path, to allow for different forces to beapplied to the garage door, or even for no restrictions on the force tobe applied, such as at the beginning or the end of the travel path.

In other situations, the controller 14 is configured to mathematicallycompare only discrete samples of the replicated force profile patternsfor different portions of the travel path, rather than for the entiretravel path.

Utilizing this so-described second embodiment of the force monitoringmethod of the present invention, as opposed to an approach that is basedsolely upon the presence or absence of force spikes in the monitoredforce factor profile pattern, not only reduces the number of needlessdoor travel interruptions, but enables responses to abnormal occurrencesthat may not otherwise be responded to. For example, in the describedjack shaft type motor drive assembly, in the event of the unspooling ofthe cable(s) from the drum, and the consequent loss of cable tension,the force monitoring method of the present invention will detect suchevent as an abnormal occurrence, resulting in immediate motor stoppageand reversal, restoring the tension as the door returns to its openposition.

In accordance with a feature of the force monitoring method of theinvention, the correlation coefficient can be defined, for example, as anumber in the range of 0 to 1, with 0 indicating a 0% degree ofcorrelation (i.e., a complete lack of correlation) between the currentlymonitored force profile pattern and the “good” stored force profilepattern, and with 1 indicating a 100% degree of correlation (i.e., aperfect match) between the currently monitored force profile pattern andthe “good” stored force profile pattern. If the pre-set acceptablecomparison criteria is then programmed into the controller 14 to be lessthan a perfect match of the patterns, for example a 0.8 correlationcoefficient (i.e., an 80% degree of correlation), then the controller 14causes the motor 18 to stop, or to stop and reverse, when the degree ofcorrelation between the compared profile patterns is less than 80%, butnot if it is at 80%, or higher. Of course, the acceptable comparisoncriteria can be pre-set, higher or lower than 80%, depending upon thedesired sensitivity, and can also be set at variable percentagesdepending upon the location(s) in the defined travel path.

In accordance with alternate embodiments, the controller 14 isconfigured to begin the comparison of the force profile patterns after adelay period of time after, rather than at, start-up. Moreover, theinitial stored “good” force profile pattern may be generated duringeither a “learn” mode or “operate” mode of the controller 14.

The correlation coefficient can be determined in a variety of differentways. As one preferred approach, the correlation coefficient r² iscalculated using sums of squared deviations from mean values.Specifically, using X as the set of values of the known good forceprofile, X′ as the measured set of values of the currently monitoredforce profile, X and X′ as their respective means, and n as the numberof samples, the correlation coefficient r² can be mathematicallydetermined as follows:

$r^{2} = \frac{{\Sigma \; {XX}^{\prime}} - {n\; \overset{\_}{{XX}^{\prime}}}}{\left( {{\Sigma \; X^{2}} - {n\left( \overset{\_}{X} \right)}^{2}} \right)\left( {{\Sigma \; X^{\prime 2}} - {n\left( \overset{\_}{X^{\prime}} \right)}^{2}} \right)}$

While the component sums used to calculate r² may be used to separatelycalculate a fitted curve Y=AX′+B, calculation of this curve and the setsof values for A and B is not necessary for this approach.

Using this mathematical formulation affords several advantages. For one,the force monitoring function of this embodiment of the invention isindependent of linear relationships between X and X′. In addition, thistechnique allows the introduction of “scaling” or “offset” of valueswhich could be caused by environmental variations, such as temperaturedifferences. When these parameters change, although the currentlygenerated force profile itself changes, the corresponding r² value staysthe same.

To help illustrate these advantages, shown in FIG. 8A is a graph of thecomparison of the stored force profile pattern (Profile 82) of a priorsuccessful garage door run with the force factor profile pattern(Profile 84) of the currently monitored garage door run, and shown inFIG. 8B is the resulting correlation coefficient. It is to be noted thatalthough the two patterns differ at points, the correlation coefficientremains relatively constant around 0.9 until the differences between thecompared force factor profile patterns become greater, at which pointthe correlation coefficient falls below 0.8. Shown in FIGS. 9A and 9Bare graphs of the force factor profile patterns for the same runs, butscaled and offset, illustrating the essentially identical resultingcorrelation coefficient, and therefore the inherent insensitivity toGaussian noise.

The graphs of FIGS. 10A and 10B illustrate the comparison of the twoforce factor profile patterns, stored force factor profile pattern(Profile 102) and currently monitored force factor profile (Profile104), utilizing the motor current as the force factor. FIGS. 10A and10B, respectively show the raw measured motor current comparison of thetwo force factor profile patterns, and the consequent correlationcoefficient r² resulting from the garage door's impact with a trueobstruction during the currently monitored run. The graphs in FIGS. 11Aand 11B show equivalent plots for the same data with random noise atlevels +/−25% of the median.

In FIGS. 12A and 12B, least-squares prediction (Prediction 1206) stayswithin a constant margin (prediction error 1208) of the measured valuesof the current run (Profile 1204). The correlation coefficient r² dropsto levels indicating anomalous barrier travel conditions. Here, as well,the correlation coefficient approach shows good results under scaling,offset, and noise, as reflected in FIGS. 13A and 13B. These Figures showthe same profile patterns of FIGS. 12A and 12B, but also includingnoise. Notwithstanding, the resulting correlation coefficient reflectsthe presence of the anomalous barrier travel conditions.

Alternative techniques may be programmed into the garage door operatorcontroller to determine the correlation coefficients. For example, onemay use either a Pearson correlation, Kendall rank correlation, Spearmancorrelation, or a Point-Biserial correlation, or any combinationthereof, as a substitute for the preferred mathematical formulationpreviously described.

As an alternative to comparing a currently monitored force factorprofile pattern with a stored force factor profile pattern from a priorsuccessful run, a currently monitored force factor profile pattern maypreferably be compared with a model of a force factor profile pattern.The model is initially generated by performing a linear least squaresfit to a known “good” monitored force factor profile pattern (i.e.,during a barrier run where obstructions or abnormal occurrences were notencountered). As each currently monitored force factor profile patternis compared to the model to determine the correlation coefficients, andassuming a programmed pre-set acceptable comparison criteria of 0.8 (or80% degree of correlation), if the determined correlation coefficient isat least equal to, or greater than, 0.8, then the currently monitoredforce factor profile pattern is incorporated into the model by expandingthe linear least squares fit that generates the model to include thedata from the currently monitored force factor profile pattern.Therefore, the model is continually updated over time.

The above described embodiment of the force monitoring method of theinvention has been described using motor current as the force factor,motor current being a typical measure of motor force where the motor 18is a DC motor. In installations where the motor 18 is an AC motor, thevery same correlation techniques described above may be applied tomeasure the degree of correlation, although using, as one alternativepreferred force factor, rotational speed of the motor shaft, motor forcebeing inversely proportional to rotational speed of the motor shaft. Arotary encoder, of a type well known to those of ordinary skill in theart, may be used to directly measure the rotational speed of the outputshaft of motor 18 in terms of revolutions per minute. This rotationalspeed of the motor is sampled over time to produce a speed profilepattern. Comparison of the speed profile pattern associated with a priorsuccessful garage door run is then made with respect to the speedprofile pattern associated with the currently monitored run in the samemanner as previously described in order to determine the correlationcoefficient.

While the monitoring embodiments of the present invention have beendescribed in the context of a limited number of situations, thoseskilled in the art, having the benefit of this disclosure, willappreciate that other variations of these embodiments will be readilyapparent that will also embody the principles of the monitoringembodiments of the present invention. Accordingly, the scope of theinvention shall be limited only by the appended claims.

1. A movable barrier opener system, comprising: a motor for moving abarrier along a defined travel path; a movable barrier operatorcontroller configured to: initially define and store a first movablebarrier behavioral profile indicative of a successful barrier run alongthe defined travel path, without barrier travel interruption, whereinthe first movable barrier behavioral profile includes at least oneposition factor; subsequently define a second movable barrier behavioralprofile indicative of a currently monitored barrier run along thedefined travel path, wherein the second movable barrier behavioralprofile includes the at least one position factor; drive the motor tomove the barrier and provide periodical reversal pulses to the motor;compare the first and second movable barrier behavioral profiles todetermine a door position discrepancy between the position factor of thefirst movable barrier behavioral profile and the position factor of thesecond movable barrier behavioral profile, and interrupt the operationof the motor, and therefore barrier travel, only when the door positiondiscrepancy is indicative of an anomalous barrier travel condition. 2.The movable barrier opener system of claim 1, wherein the first movablebarrier behavioral profile is either set at the factory or as aconsequence of a successful barrier run prior to the currently monitoredbarrier monitor run.
 3. The movable barrier opener system of claim 1,wherein the position factor comprises at least one of motor current andmotor shaft position coinciding with a peak motor current.
 4. Themovable barrier opener system of claim 1, wherein the movable barrieroperator controller is configured to determine the door positiondiscrepancy between the first and second movable barrier behavioralprofiles for a partial portion of a range of travel of the movablebarrier corresponding to a plurality of periodic reversal pulses.
 5. Amovable barrier opener system, comprising: a motor for moving a movablebarrier along a defined travel path; a jack shaft motor drive assemblyfor rotating a jack shaft and one or more cable drums rigidly attachedto the jack shaft, with one or more cables disposed about the drums withthe free end of each cable attached near the bottom of the movablebarrier, the rotation of the jack shaft in a defined directionconfigured to lower the movable barrier; a movable barrier operatorcontroller configured to: compare a first movable barrier behavioralprofile, corresponding to motor current and motor shaft position, andindicative of a successful door run, without door travel interruption,along the defined travel path, with a second movable barrier behavioralprofile, also corresponding to motor current and motor shaft position,indicative of a currently monitored movable barrier run along thedefined travel path; and stop the motor when the comparison of thesecond movable barrier behavioral profile with the first movable barrierbehavioral profile indicates a loss of tension in the one or morecables.
 6. A movable barrier opener system, comprising: a motor formoving a barrier along a defined travel path; a movable barrier operatorcontroller for controlling the operation of the motor, the controllerconfigured to: define and store a first movable barrier behavioralprofile indicative of a successful barrier run, without motorinterruption, along at least a portion of the defined travel path;generate a second movable barrier behavioral profile indicative of asubsequent monitored barrier run along the same portion of the definedtravel path; and compare the second movable barrier behavioral profilewith the first movable barrier behavioral profile to determine whetheran accumulated door position discrepancy satisfies a pre-set acceptabledeviation criteria.
 7. The movable barrier opener system of claim 6,wherein the pre-set acceptable deviation criteria is at least one ofprogrammed into the controller, set by a user at the time ofinstallation of the movable barrier operator, and set proportional to amass of the movable barrier.
 8. The movable barrier opener system ofclaim 6, in which the controller is configured to compare theaccumulated door position discrepancy to the pre-set acceptablecomparison criteria programmed into the controller, the controller alsoconfigured to stop the motor when the accumulated door positiondiscrepancy is not within the pre-set acceptable comparison criteria. 9.A method of operating a movable barrier opener system, the methodcomprising the steps of: a) directing a motor to move a barriersubstantially along a defined travel path; b) sensing current drawn bythe motor during the movement of the barrier substantially along thedefined travel path; c) providing momentary reversal pulses to the motorduring the movement of the barrier substantially along the definedtravel path and determining the motor shaft position associated withcorresponding peaks in the current; d) calculating a door positiondiscrepancy measurement comprising a difference between at least onemotor shaft position associated with at least one peak in the currentand at least one motor shaft position associated with at least one peakin the sensed current of at least one past good run of the barrier; ande) directing the motor to cease movement, or cease and reverse movement,of the barrier upon the door position discrepancy measurement beingoutside of pre-set acceptable deviation criteria.
 10. The method ofclaim 9, wherein the calculating the door position discrepancymeasurement further comprises summing a plurality of the differencesover time.
 11. A method of operating a movable barrier opener system,the method comprising the steps of: a) directing a motor to move abarrier substantially along a defined travel path; b) sensing currentdrawn by the motor during the movement of the barrier substantiallyalong the defined travel path; c) providing momentary reversal pulses tothe motor during the movement of the barrier substantially along thedefined travel path and determining the motor shaft position associatedwith corresponding peaks in the current; d) measuring at least one ofthe peaks in the current; e) calculating a difference between themeasured at least one peak in the current and at least one previouslymeasured peak in current of at least one past good run of the barrier;and f) directing the motor to cease movement, or cease and reversemovement, of the barrier upon the difference being outside of pre-setacceptable deviation criteria.
 12. A movable barrier opener system,comprising: a motor for moving a barrier along a defined travel path; amovable barrier operator controller configured to: initially define andstore a first force factor profile pattern indicative of a successfulbarrier run along the defined travel path, without barrier travelinterruption, subsequently define a second force factor profile patternindicative of a currently monitored barrier run along the defined travelpath, compare the first and second force factor profile patterns todetermine a degree of correlation, namely the correlation coefficient,between the first and second force profile patterns, and interruptoperation of the motor, and therefore barrier travel, in response to thecorrelation coefficient being indicative of an anomalous barrier travelcondition.
 13. The movable barrier opener system of claim 12, whereinthe first force profile pattern is either set at the factory or as aconsequence of a successful barrier run prior to the currently monitoredbarrier monitor run.
 14. The movable barrier opener system of claim 12,wherein the first and second force factor profile patterns depend upon aforce factor consisting of one of motor torque, motor current, motorspeed, motor voltage, or back EMF, or combinations thereof.
 15. Themovable barrier opener system of claim 12, wherein the movable barrieroperator controller is configured to determine the degree of correlationbetween the first and second force profile patterns by calculating acorrelation coefficient using sums of squared deviations from meanvalues of the first and second force profile patterns.
 16. A garage dooropener system, comprising: a DC motor for moving a garage door along adefined travel path; a jack shaft motor drive assembly for rotating ajack shaft and one or more cable drums rigidly attached to the jackshaft, with one or more cables disposed about the drums with the freeend of each cable attached near the bottom of the garage door, therotation of the jack shaft in a defined direction configured to raisethe garage door; a garage door operator controller configured to:compare a first force factor profile pattern, corresponding to motorcurrent, and indicative of a successful door run, without door travelinterruption, along the defined travel path, with a second force factorprofile pattern, also corresponding to motor current, indicative of acurrently monitored garage door run along the defined travel path; andstop the motor when the comparison of the second force profile patternwith the first force profile pattern indicates a loss of tension in theone or more cables.
 17. A movable barrier opener system, comprising: amotor for moving a barrier along a defined travel path; a movablebarrier operator controller for controlling the operation of the motor,the controller configured to: define and store a first force factorprofile pattern indicative of a successful barrier run, without motorinterruption, along at least a portion of the defined travel path;generate a second force factor profile pattern indicative of asubsequent monitored barrier run along a same at least the portion ofthe defined travel path; and comparing the second force factor profilepattern with the first force factor profile pattern to determine thecorrelation coefficient.
 18. The movable barrier opener system of claim17, in which the controller is configured to compare the correlationcoefficient to pre-set acceptable comparison criteria programmed intothe controller, the controller also configured to stop the motor whenthe correlation coefficient is not within the pre-set acceptablecomparison criteria.
 19. A method of operating a movable barrier openersystem, the method comprising the steps of: a) directing a motor to movea movable barrier substantially along a defined travel path whilesensing current drawn by the motor and, based upon the sensed current,generating a current consumption curve; b) determining a degree ofcorrelation between the current consumption curve and a currentconsumption curve indicative of a successful barrier run along thedefined travel path, without barrier travel interruption, as the currentconsumption curve is generated; and c) directing the motor to ceasemovement, or cease and reverse movement, of the movable barrier upon thedegree of correlation being outside of pre-set acceptable comparisoncriteria.
 20. The method of operating the movable barrier opener systemof claim 19, wherein the pre-set acceptable comparison criteria is atleast one of programmed into the controller, set by a user at the timeof installation of the movable barrier operator, and set proportional toa mass of the movable barrier.